Devices that create a loud report and simultaneously project materials utilizing compressed air or gas are well known to the art. These devices often use a burst disk which allows for the gradual increase in pressure in a chamber containing the material to be projected, and the sudden, but predictable release of the pressure and perhaps entrained material through the orifice, newly defined, by the disintegration of the burst disk.
The earliest such device is likely the popgun, which utilizes a cork which serves both as the burst disk and the material that is projected, at the sudden release of pressure.
Another such device is the spud gun or potato gun. These devices are similar to the pop guns, having a piston that incrementally increases pressure behind the combination burst disk and projected material, that is, the plug of potato pressed into the end of the barrel. At first, like the cork of the pop gun, the potato plug frictionally grips the barrel interior, with sufficient force to resist the rising pressure created by the approaching piston. At some point however the force of the compressed gas attempting to expel it from the barrel is of sufficient force, that the static friction is suddenly and catastrophically overcome, causing the plug to suddenly accelerate as the compressed gas continues to act on it. When the expanding gas, behind the cork or potato plug meets the static air, there is often a shock wave created and a loud pop. It is important to note that the gas first escaping these guns is slowed by the slower moving projectile, in front of the gas.
U.S. Pat. No. 2,831,475 by Richard I. Daniel, discloses a pop gun that has a disk that allows for the pressure to build, as a spring loaded piston is released, by a trigger, to travel down a barrel, at the end of which is a flexible split disk that at first resists the ever increasing load of the gas, but at some calculated force, suddenly deforms, and just as suddenly releases the accumulative air pressure—producing a loud report. After the release of pressure the split disk reforms for the next shot, obviating the necessity of replacing a disintegrated burst disk after each discharge.
U.S. Pat. No. 3,422,808 by Bernhard Stein, et al. discloses a gun in which compressed air accumulates in the end of a chamber, separated from a piston and payload by two closely spaced membranes, held at an air pressure higher than ambient. The two membranes act as a burst disk, resisting the accumulating external air pressure, but suddenly and catastrophically failing, allowing the compressed air to act on the piston, projecting it and the payload to the end of the barrel, where the piston is braked, while the payload continues its flight out of the barrel. In this case the failure of the burst disk is triggered by allowing the pressure between the disks to drop, effectively increasing the relative pressure of the accumulating air pressure at the end of the chamber opposite the piston and payload. While this patent describes a method of projecting an object, it does not produce a significant sonic report as the gas immediately escaping from the burst disks, is blocked by the projectile.
U.S. Pat. No. 3,428,087 by Igino Capriolo et al. discloses a compressed air pressure gun, similar to U.S. Pat. No. 3,422,808, referred to above, but instead of just two membranes, there are several. Again the gas, first escaping from the burst disk, is blocked by the projectile, resulting in a very quiet sonic report.
U.S. Pat. No. 5,015,211 by Tyrone J. Reveene, discloses a confetti cannon that relies on a blast of gas released from a compressed gas canister. This cannon relies on a rapid evacuation of the gas from the canister into the barrel of the cannon and does not utilize a membrane or burst disk to build pressure in the barrel prior to launch. This cannon is designed to project confetti plugs high in the air without concern for creating a loud sonic report or sonic shock wave. Again the projectile is in advance of the first compressed gas being released into the ambient air, and therefore slows the escaping gas, and consequently reducing the volume of the sonic report.
U.S. Pat. No. 6,749,481 by Leong Kheng Yap, et al. discloses confetti and particulate cannon that is designed to project those materials and purports to accompany the projection with a sonic report. Unfortunately, it has been found that the method taught by Yap et al. are not suitable for creating a cloud that looks like a smoke cloud, while at the same time creating a loud bang that simulates an explosion of an explosive device, such as an artillery shell or landmine. The reason for this is that the pressure builds behind the confetti or particulate, which acts to compress it and tends to form it into a plug. When the burst disk finally fails, releasing the confetti or other payload, those materials tend to defuse the shock wave that would otherwise be produced if those materials were not present. The payload then slows the advancing of the gas that would otherwise create a sock wave at the gas/air interface, if not so impeded. The other disadvantage with this method is that the compressed payload has a tendency to eject from the barrel of the cannon as a plug. For those applications where one requires the immediate creation of a diffuse cloud of smoke or cloudlike zone, near the end of the barrel, it is preferable to have the compressed air create a fluidized bed within the cannon chamber, so that as it is expelled, it does so a highly aerated manner.
It is important to note that the requirements for creating a loud sonic report are different from those that are ideal for transporting the payload. Generally the creation of a shock wave that produces a loud report is best accomplished by creating a short, high pressure, high velocity pulse. However, the transport of the payload generally requires a longer duration flow of air that entrains the particles and projects them out of the gas projector.
What is needed therefore is a two step method whereby: first, the sonic shock wave is produced by the gas being released by the burst disk, unimpeded by payload. Second and later, the payload is transported by being entrained by lower pressure, longer duration gas movement.
Another difficulty with the devices of the prior art is the tendency for their mechanism to become fouled with particulate matter or other payload material.
It is the purpose of this invention to produce a high pressure pulse of compressed gas, unimpeded by the payload, at that moment when a valve or the burst disk substantially instantaneously opens.
It is the purpose of this invention to fluidize the payload of particulate matter or confetti prior to, and/or it is being ejected from the barrel of the gas projector.
It is the purpose of this invention to concentrate, project and direct the sonic energy and/or shock wave, to enhance the sonic report.
It is the purpose of this invention to create a diffuse cloud or smoke cloud that accompanies the loud sonic report, both to simulate the effects of a pyrotechnic explosion.
It is the purpose of this invention to create one or more vortexes that will more efficiently entrain particular matter and transport it for longer distances, and also to create an percussive force that will simulate the air blast of a real explosion, although at much lower and safer energies.
It is the purpose of this invention to separate the mechanism from the particulate matter or payload by the radial expansion and contraction of a simple and inexpensive “O” ring.
It is the further purpose of this invention to create preferred embodiments that have the appearance of general military ordinance and pyrotechnic devices; and further to create realistic sounds and visual effects that simulate detonations of those real devices.